To echo Dave's comments, it is probably not prudent or cool, therefore maybe not wise, but I'm here to tell you it's safe. I always have tried not to, but seems like I almost always do, at least working in browser or Excel, and have only once out of hundreds of times had an issue. And, as our leader said, that time SD returned an error, which simply re-updating (while staying off the other appls.) took care of. (Also, that was under a 1.nn version of SD)

Also, backups used to take much longer....which increased my temptation to do other things while they were happening. SD is now much faster than at the beginning, and my B/U drive is 7200 rpm, not 4500, so it's easier for me to refrain now. But I still don't.